Sample Program - PERFORM

An example program that demonstrates how the first format of the PERFORM may be used to change the flow of control through a program.

$ SET SOURCEFORMAT"FREE"
IDENTIFICATION DIVISION.
PROGRAM-ID. PerformFormat1.
AUTHOR. Michael Coughlan.
* Illustrates how the first format of the PERFORM may
* be used to change the flow of control through a program.
* Use the output of this program to get an understanding of how
* this format of the PERFORM works.

PROCEDURE DIVISION.
TopLevel.
DISPLAY "In TopLevel. Starting to run program"
PERFORM OneLevelDown
DISPLAY "Back in TopLevel.".
STOP RUN.


TwoLevelsDown.
DISPLAY ">>>>>>>> Now in TwoLevelsDown."
PERFORM ThreeLevelsDown.
DISPLAY ">>>>>>>> Back in TwoLevelsDown.".


OneLevelDown.
DISPLAY ">>>> Now in OneLevelDown"
PERFORM TwoLevelsDown
DISPLAY ">>>> Back in OneLevelDown".


ThreeLevelsDown.
DISPLAY ">>>>>>>>>>>> Now in ThreeLevelsDown".